Salmonella landau as a live vaccine against Escherichia coli O157:H7 investigated in a mouse model of intestinal colonization.

The present study was performed to assess the potential of a humoral mucosal immune response directed against the O157 antigen of Escherichia coli O157:H7 to prevent intestinal colonization by the pathogen. To this end, mice were gavaged with inocula of Salmonella landau, a Salmonella strain that naturally expresses the O157 antigen. Salmonella landau was avirulent for mice. Despite this, mice exposed to S. landau developed high titres of serum and coproantibodies against the O157 antigen. These mice, compared with controls, demonstrated some ability to resist transient intestinal colonization by an oral inoculum of an isolate of E. coli O157:H7. These findings suggest that a local immune response directed against the O157 antigen might increase host resistance to this pathogen.